Introduction
The report aims to analyse the four pollutants observations made by
25 air quality monitors that are scattered across New Your city. The
measurements were made betwenn 01-01-1990 and 31-12-2019, and the
pollutants analysed here are:
- Carbon monoxide (CO) [ppm]
- Sulfur dioxide (SO2) [ppb]
- Ozone (O3) [ppm]
- Nitrogen dioxide (NO2) [ppb]
ppm: parts per million ppb: parts per billion
Data source: NOAA
Historical Air Quality
See also sql_code file to see
how the database was queried.
Data Processing
Looking into the first row:
## site_num parameter_name concentration date_local longitude latitude
## 1 0071 Carbon monoxide 1.173684 1990-01-01 -73.98368 40.69578
## 2 0011 Sulfur dioxide 14.712500 1990-01-01 -73.94722 40.73277
## 3 0073 Sulfur dioxide 17.958333 1990-01-01 -73.90958 40.81149
## 4 0056 Carbon monoxide 1.568421 1990-01-01 -73.96661 40.75912
## 5 0063 Ozone 0.024706 1990-01-01 -74.01264 40.71149
## 6 0056 Carbon monoxide 1.608696 1990-01-01 -73.96661 40.75912
What is the sampling time period?
## min max
## 1 1990-01-01 2019-12-31
How many measurements were made and what are their time period?
## parameter period observations
## 1 Carbon monoxide 1990-01-01 to 2019-12-31 104192
## 2 Sulfur dioxide 1990-01-01 to 2019-12-31 102677
## 3 Ozone 1990-01-01 to 2019-12-31 50026
## 4 Nitrogen dioxide (NO2) 1990-01-01 to 2019-12-31 38892
## 5 Outdoor Temperature 1992-06-09 to 2019-12-31 21793
What is the average number of observations between 1990 and
2019?
- On average, Carbon Dioxide had the large number of
observations.
## # A tibble: 5 x 2
## parameter_name mean
## <chr> <dbl>
## 1 Carbon monoxide [ppm] 4.76
## 2 Nitrogen dioxide [ppb] 3.59
## 3 Outdoor Temperature[°F] 2.24
## 4 Ozone [ppm] 4.57
## 5 Sulfur dioxide [ppb] 4.65
How frequent were the measurements throughout the years?
- CO and SO2 had approximately 2500 observation per year until around
the year 2000, when the total number of observations drop to around
1000.
- O3 observations kept almost constant over the year (around 1500
observations per year) with a peak between 1999 and 2001.

Data Analysis
How the concentration of pollutants evolve over time?
- The trend of all pollutants, but ozone, seams to decrease over
time.
- Specially Sulfur dioxide (SO2) and Ozone (O3) present regular
oscillation peaks and valleys.

Have the peaks and valleys of O3 and SO2 a pattern?
- Looking closely between 2010 and 2016, O3 presents a pattern where
peaks occur round the middle of the year and valleys around the turning
of the years (Figure A).
- Figure B shows the frequency distribution of the
months that presented mean concentration over 0.04 ppm of O3 (black line
in Figure A) within 1990 and 2019. Clearly, monitors
measure on average higher concentrations of O3 between April and
September.
- A mirror phenomena occurs when measuring SO3. Within the first and
last months, monitors detect a higher concentration of SO3. For
instance, Figure C show the weave-pattern of SO3
between 1990 and 1996, and Figure D shows the frequency
distribution of the months that have daily average concentration above
30 ppb between 1990 and 2019.

What is the linear correlation among the parameters between 1990 and
2019?
- CO, SO2 and NO2 have a strong correlation among themselves. That may
indicate that these tree pollutants share common sources.
- Ozone (O3) and temperature also present strong correlation. It is
common knowledge that ozone is unstable substance on atmosphere pressure
and high temperatures. Thus, one could expect that O3 and temperature
have negative correlation, if the source of ozone were constant over the
years. However, the positive correlation of 0.6 indicates the
temperature is positive correlated with the amount of O3 released on New
York proximity.

What are the four most relevant Ozone observations and their
neighborhood?
- Neighborhoods Financial District and Latourette Park measure
consistently higher concentration of ozone than the city average.
- The oposite is observed for the neighborhoods Bronx Park and
Flatiron.

What are the four most relevant Carbon Monoxide observations and
their neighborhood?
- Neighborhoods Tribeca and Downtown Brooklyn measure slightly higher
concentration of CO than the city average.
- The oposite is observed for the neighborhoods Midtown and Bronx
Park.

What are the four most relevant Sulfur Dioxide observations and
their neighborhood?
- Neighborhoods Midtown and Flatiron District measure higher
concentration of SO2 than the city average no the 90s and part of the
2000s.
- The monitor located in Flushing detected consistently lower values
than the city average.
- The monitor located in Longwood detected SO2 concentrations around
average. Around the year 2000 SO2 yearly average crosses downwards the
city average.
- The City Average decreasing trend may be biased because the monitors
with historical data from the 90s to middle 2000s are different than the
one that have historical data from middle 2000s on wards. However, the
trends of monitors separately have a downward trend.

What are the four most relevant Nitrogen Dioxide observations and
their neighborhood?
- Midtown monitor measured consistently concentrations of NO2 above
the city average.
- Contrarily, the monitor by FLushing measured consistently yearly
mean concentration below city average.
- The monitor located in Bay Side neighborhood has data of only four
years.

Geospatial Visualization
Air quality monitors across NY
CO monitors across New York
Relative CO pollution among the neighborhoods of NY between 1990 and
2000
In the map below, the darker the red, the higher the CO average
concentration in ppm between 1990 and 2000. Since the majority of the
neighborhoods do not have a monitor, their CO concentration are
estimated through weighted average of all the other monitors. The
weights are function of the distances to the other monitors (Read more
here).
The nearst monitor distance, which is displayed together of
the estimation and neighborhood name, can be interpreted as a
measurement of approximation occur. It is expected that, the closer a
neighborhood is from a monitor, the more accurate is the estimation of
the reality. Looking to the Choropleth
below, it is possible to conclude:
- Manhattan and proximity have the highest values of CO on average
between 1990 and 2000.
- Neighborhoods near to the cost (most southern) have on average the
lowest concentrations of CO.